when I use that CSS the space for the title is gone. There is still a little padding at the top, but the title area is gone. Test it out like this.
1) Open a browser window and go to the ATO and remove the css and do a save.
2) open a new tab and go view a page
3) go back and add in the CSS and save
4) Open a NEW tab and view the page
now swap back and forth between the page with the title and the page without, see any difference?

As for the sidebar border, The center area is a one row table, the cells are the sidebars and the middle area. The border (dash lines between the sidebar and middle area) goes from top to bottom of the table row which happens to be the heifht of the sidebars/middle area.